Cytopathological diagnosis of bladder cancer is dependent on the microscopic finding of nuclear abnormalities in exfoliated bladder cells. This technique is very subjective and the cellular description can often vary from pathologist to pathologist. The cytological diagnosis of low grade bladder cancer is especially difficult because the cellular changes are minimal. Flow cytometry (FCM) has been used to diagnose bladder cancer and appears to be useful in the diagnoses of high grade bladder tumors by measuring changes in DNA content. Low grade bladder cancer and benign papillomas have a diploid DNA content and are therefore difficult to differentiate from normal bladder uroepithelial cells. Inflammatory cells present in a bladder specimen have diploid DNA content and can mask the presence of tumor cells when analyzed by single parameter DNA analysis. Contaminating inflammatory cells are observed frequently in bladder specimens from patients receiving Bacillus Calmette- Guerin (BCG) immunotherapy. In an attempt to address the problem of inflammatory cell contamination, this study will use bladder tumor associated monoclonal antibodies (Mabs) in an indirect immunofluorescence assay to immunoselect tumor cells in bladder washings (BW) and voided urine (VU) specimens. Immunoselection of the tumor cell population and separation from the inflammatory cell populations will permit accurate analysis of the tumor cells for DNA content and other cell parameters. In addition to DNA content, the tumor cells will be analyzed for cell cycle phase (percent S phase) and nuclear roundness. The results of this flow cytometric analysis will be compared to the cytopathological diagnosis, stage and grade of the tumor, cystoscopic observation, treatment and the patient's clinical status. Periodic testing will determine if the FCM assay is more accurate in monitoring the effects of therapy or detecting recurrent tumor prior to any cytological or clinical signs. The long term goal of this study is to develop a multiparameter cytometric method that will enhance the accurate diagnosis of bladder tumors, including those of low histological grade and which can be used as a technique to effectively monitor patient therapy and prognosis.